Remove QWeakPointer::operator->

operator-> was only defined if QWEAKPOINTER_ENABLE_ARROW is defined.
However, even in that case it would call QWeakPointer<T>::data, which
does not actually exist. Take this as an indicator that nobody actually
uses operator->, and remove the code completely.
Note that the QWEAKPOINTER_ENABLE_ARROW was not documented, and neither
was operator->.

Change-Id: I2f4aa961a64281542c8c1b248a993e83471c059d
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/corelib/tools/qsharedpointer_impl.h

@@ -634,10 +634,6 @@ public:
     // std::weak_ptr compatibility:
     inline QSharedPointer<T> lock() const { return toStrongRef(); }
 
-#if defined(QWEAKPOINTER_ENABLE_ARROW)
-    inline T *operator->() const { return data(); }
-#endif
-
     template <class X>
     bool operator==(const QWeakPointer<X> &o) const noexcept
     { return d == o.d && value == static_cast<const T *>(o.value); }